The present invention relates to electronic devices, and in particular to an electronic device comprising at least one circuit board, an interference screen fixed to said circuit board, and a power source comprising a first and a second terminal. The invention relates also to an interference screen for improving the electromagnetic compatibility of said electronic device.
When the features of electronic devices are compared, the fact that a device takes little room, is comfortable to carry and operates without failures also in demanding operating conditions, has become a significant factor. Because devices also are supposed, however, to perform all the time more and more complicated tasks, fitting the components contained in a device into a desired space is a challenging task requiring complicated optimizing. In order to keep prices under control, the solutions should also be suitable for mass production as far as possible.
A component that makes optimizing difficult is the power supply supplying to a device the power required for operating. For example in mobile stations the device comprises, in addition to a large rechargeable battery, also a smaller back-up power supply for securing the power supply to continuously maintained functions even when the actual battery is discharged. Compared with other electronic components, a back-up power supply is large and thus takes up a lot of space when installed on a circuit board.
Furthermore, a back-up power supply does not necessarily endure the temperature in a reflow-oven, and thus it often has to be mounted on a circuit board only after the oven treatment. This kind of solution is used e.g. in communicator model Nokia 9000, in which the protruding terminals of the power supply are soldered manually directly on the circuit board. The method provides a good result, but unnecessarily complicates the manufacturing process.
In certain consumer electronics devices and for example in Nokia 9110 model communicators it has been arranged directly on the circuit board a stackable metal holder, into which a battery used as a back-up power supply can be slipped in assembly stage after oven treatment, i.e. the manual soldering stage impeding production is not required. Such a solution is more functional from the production and maintenance point of view, but it still takes up relatively much space on a circuit board.
Now it has been invented an electronic device, where the effect of the above problems has been significantly reduced. According to a first aspect of the invention there is provided an electronic device, comprising
at least one circuit board;
an interference screen to be connected to said circuit board;
a power supply, comprising a first terminal and a second terminal;
wherein
said interference screen comprises means for fixing the power supply, to the interference screen in such a way that an electrical connection is formed between the interference screen and the first terminal of the power supply.
According to a second aspect of the invention there is provided an electronic device, comprising:
at least one circuit board;
an interference screen arranged to be fixed to said circuit board;
a battery, comprising a first terminal and a second terminal; and
a holder for holding the battery in relation to the interference screen so that an electrical coupling is formed between the interference screen and the first terminal.
By using a solution according to the invention it is possible to mount a power supply in a device without unnecessarily taking up space on the circuit board comprising the equipment. The solution is well suited for series production, and as there are no soldered connections, it also makes the servicing of the power supply easier. In the invention the mounting of the power supply utilizes a fixed construction, made of conductive material, used for protecting the device from electromagnetic interference. By using the construction the power supply is fixed in a desired place, and at the same time the power supply is connected via said construction to a desired potential.
In a solution according to the invention it is utilized the mechanical properties of the screen for fixing the power supply in place and the conductive properties of the screen to establish the electrical connection of the power supply. For example in mobile stations it is possible to utilize the invention and place a back-up power supply outside a circuit board and thus significantly save space on the circuit board. The attaching of a power supply is based upon pressing constructional parts against each other, and thus a power supply can be stacked in place in the assembly stage of a device and the power supply need not be soldered in place. When servicing, the arrangement is easy to dismantle and reassemble, and accordingly e.g. a damaged power supply is easy to replace.
An object of the invention is also an interference screen according to claim 12 for improving the electromagnetic compatibility of an electronic device. Said electronic device comprises at least one circuit board; and a power supply comprising a first terminal and a second terminal, wherein the screen comprises a fixing part for fixing a power supply to the screen in such a way that an electrical connection is formed between the screen and the first terminal of the power supply.